I know that I am new here, so this may have already been addressed. I tried to search for this and did not answer my question.

If I can go and buy an aftermarket gizmo (not a cheap one either, about $500) that I hook up to my Taco and reprogram the motor so it has more power, gets better mileage, etc..., then why didn't the manufacterer do that in the first place? It seems like MPG and HP are pretty big selling factors for a truck, don't you think that Toyota would have done this??

One ad for such a product makes the following claims:

Packs up to 57hp extra into the pedal of gas-fueled rides
Vehicles testing experienced gains of up to 1.5 to 6 MPG
Expertly tuned across the power band for extra juice at any RPM
Mapped to keep damaging temps low without de-fueling that kills power
Engineered to thrill—even when towing up to 10,000lbs.
Optimized transmission settings always have you in the right gear

I would think that the guys who spent years designing, building, and testing this truck probably know more about how the motor and transmission should be configured than a company that has one box that promises all of these things above for any car/truck/van/motorcycle/bicycle/rickshaw. If Toyota could deliver a Taco that got and EPA 27 MPG and had 50 more HP, don't you think they would?? Like I said at the beginning I must be missing something, please let me know what it is.

well, alot of the 'tuners' you see in places like ebay are fakes and make outrageous claims, but companies like Banks, Bullydog, Hypertec and others really can get most of those claims accomplished(on diesel trucks). I think it would have to do with emissions regulations as well as long term reliabilty that keeps manufacturers from tuning their vehicles differently.